#10 Paul Allen

2011 net worth:$13 Billion

2010 net worth: $13.5 Billion

Source: Microsoft, investments

Co-founder of Microsoft Paul Allen owns Vulcan which invests in various tech ventures. Allen also owns the Seattle Seahawks, Portland Trailblazers, and is known for suing a handful of Silicon Valley tech giants.

#8 Steve Ballmer

2011 net worth:$14.5 Billion

2010 net worth: $14.5 Billion

Source: Microsoft

CEO of Microsoft, Ballmer, released his fastest selling version of Windows OS last year which sold 300 million copies. Although Ballmer didn't lose any of his fortune, he dropped 12 spots on the list from 33 in 2010.

#1 Bill Gates

2011 net worth:$56 Billion

2010 net worth: $53 Billion

Source: Microsoft

Microsoft founder Bill Gates would be even richer, but he is also one of the most generous people in the world. He has given away $30 billion to the Gates Foundation, a charity dedicated to fighting tuberculosis, and hunger across the world.